| disease | Knee Joint Tuberculosis |
The knee joint has a large synovial membrane area and abundant cancellous bone, along with factors such as significant weight-bearing in the lower limbs, frequent movement, and susceptibility to sprains, leading to a relatively high incidence rate. It ranks second among the subcutaneous nodules of the limb joints, following only spinal and hip joint subcutaneous nodules. Most patients are children or young adults. Due to the rich synovial membrane tissue in the knee joint, the incidence of synovial membrane subcutaneous nodules is relatively high.
bubble_chart Pathogenesis
Initially, it is mostly of the synovial membrane type, with osseous lesions often occurring in the upper tibia or lower femur, both of which can spread to the entire joint as subcutaneous nodules. The synovial membrane becomes thickened and congested, appearing slightly grayish and translucent, with some areas resembling bean dregs or fermented tofu. There may be effusion and adhesions, and granulation tissue spreads over the cartilage surface, some of which may detach due to friction, exposing the bone surface. If the epiphysis is damaged, it can lead to limb shortening deformities. Due to the lack of muscle coverage around the knee joint, muscle atrophy is evident, and swelling is pronounced, causing the joint to enlarge into a spindle shape. Abscesses are more likely to rupture and form sinuses. The disease course is prolonged and rarely self-healing, often requiring surgical treatment.
bubble_chart Clinical Manifestations
The onset is slow, with early symptoms being inconspicuous. There may be grade I joint swelling and limited mobility. Patients often seek medical attention only after a prolonged period of illness, and subcutaneous nodules around the entire joint are frequently discovered during the initial visit. As the condition progresses, swelling becomes pronounced, accompanied by muscle atrophy, joint space narrowing, bone destruction, restricted movement, pain, and tenderness. In the advanced stage, pain leads to muscular rigidity and spasms, resulting in flexion contracture of the knee joint and varus or valgus deformities. Sinus formation is common, often complicated by infection. Due to pain and deformities, patients may develop a limp or even become unable to walk.
bubble_chart Auxiliary Examination化脓性关节炎；类风湿性关节炎；创伤性关节炎
The diagnosis should be based on clinical manifestations, body temperature, erythrocyte sedimentation rate, and X-ray examinations. If necessary, a timely biopsy or animal inoculation should be performed to confirm the diagnosis. Early definitive diagnosis is crucial. Sometimes, enlargement of the femoral lymph nodes and subcutaneous nodule lesions can be observed, and biopsy of these nodules may be significant for diagnosing subcutaneous nodules of the knee joint. It should be differentiated from traumatic, suppurative, and wind-dampness-like arthritis.
bubble_chart Treatment Measures
(1) Supportive therapy and anti-tuberculosis drug treatment to improve overall health.
(2) Early bed rest and traction can rapidly alleviate symptoms. Use skin traction to keep the joint extended.
(3) For early synovial-type tuberculosis, intra-articular injection of streptomycin, 1 gram each time, 1–2 times per week for about 12 weeks. If ineffective, early surgery should be performed.
(4) Surgical therapy
1. For osseous tuberculosis, the lesion should be removed early to prevent spread to the joint.
2. For synovial-type tuberculosis, if most of the cartilage remains intact, debridement can be performed to remove the diseased synovium, suprapatellar fat, and granulation tissue on the cartilage surface. If the meniscus is involved, it should also be excised. After surgery, ensure complete hemostasis, place the affected limb on a Thomas splint with skin traction to maintain joint extension. Gradually mobilize the joint afterward, but keep it extended during rest. Continue anti-tuberculosis drugs for half a year. In children, a certain range of joint motion can often be preserved.
